Chairlifts, gondolas, trams and similar personnel carrying apparatus which are widely employed at ski resorts and the like to carry skiers and sightseers up the mountainside typically are formed with a grip assembly that secures the individual chair, gondola, etc. to an endless cable and a hanger arm which is movably supported from the grip assembly and carries the weight or load. A number of different types of grips have been developed which are suitable for securing chairs to the endless cable, and similarly, a variety of weight supporting hanger arms and frames have been devised, depending upon the structure which will carry the skier up the mountainside.
Virtually all chairlift or gondola systems require that the weight supporting hanger arm be pivotally or movably mounted to the cable grip, usually by a collar which is mounted to a hub carried by the grip assembly. It is also necessary and highly desirable to damp out relative motion between the hangar arm and grip. Damping of this relative motion is necessary in order to prevent dangerous swinging of the chairs during operation of the lift.
The most common type of damping assembly for chair lifts and the like has been to provide an annular surface on the collar of the hangar arm, or on the end of the hub, against which a friction member, such as a mating annular member, can be axially urged by a spring assembly and a lock nut. A damping assembly of this type is disclosed in U.S. Pat. No. 3,257,965. Such a frictional damping assembly, therefore, is somewhat like a spring actuated disk brake operating between the collar of the hangar arm and the hub assembly of the grip so as to damp out relative motion.
While such prior friction-based, motion damping assemblies for chairlifts or the like have functioned adequately, they have inherently been found to degrade in their damping performance at an undesirably fast rate. Thus, readjustment of the friction force and replacement of the friction member have been required more frequently than would otherwise be desirable. Additionally, some friction damping devices are so inadequate as to require auxiliary equipment to insure damping. Thus, shock absorbers are commonly added to lift systems to augment damping.